The present invention relates to an image forming apparatus adapted to enable a sheet or the like stuck in a carrier path to be removed by opening the carrier path between a feeding unit for feeding such a sheet to an image forming unit and a discharge unit for discharging the sheet carried from the image forming unit to the outside.
Digital technology has recently found its fields of application in copying machines, and attempts are being made to improve image quality through the use of laser recording. The digital copying machines are now capable of producing an image output from data transmitted from devices other than a scanner unit in a copying machine, such as a personal computer and a facsimile machine, connected through an interface.
A need arises here to produce image outputs in the same order as the associated image data inputs are received from another device or apparatus. xe2x80x9cFace-downxe2x80x9d types are currently popular; those types discharge sheet sequentially from the discharge unit so that the side of the sheet on which an image is formed looks down.
The face-down type is equipped with a carrier path through which, sheet is fed sheet by sheet from a feeding unit, such as a sheet feeding unit, situated below an image forming unit and also sheet, after an image is formed thereon, is discharged face-down from a discharge unit situated above the image forming unit. Along the carrier path extending upright between the feeding unit and the discharge unit are there provided a pair of carrier rollers, transfer device, peeler device, fixing device, and other devices, which overall complicates the structure of the apparatus. Miniaturization of the image forming apparatus is another trend recently being pursued; if moving sheet gets stuck in the carrier path as a result of a problem in the image forming apparatus, removing the stuck sheet is a troublesome task.
Japanese Patent Publication No. 8-18724 discloses an image forming apparatus having a main body which is separable into two parts with respect to the carrier path extending upright between the feeding unit and the discharge unit, one of the parts being a static body including an image forming unit, the other part being a movable body which, near the bottom thereof, is engaged rotatably to the static body via a supporting axis and which can thereby swing with respect to the static body, wherein if moving sheet gets stuck in the carrier path, the carrier path can be opened by swinging the movable body around the supporting axis, allowing the sheet to be removed from the carrier path.
In the conventional image forming apparatus, the movable body in the main body is engaged rotatably with the static body, and the movable body is swung around the supporting axis. The structure allows the carrier path to be wide open on the side opposite to the swing center, but not on the side of the swing center. Therefore, it is difficult to remove sheet stuck near the entrance of the carrier path (near the feeding unit).
Further, the entire movable body swings around the supporting axis, tracing an arc; therefore the transfer device, the carrier rollers, and other components which forms the carrier path in the movable body move tracing a curve, rather than a straight line. This makes it difficult to accurately position the aforementioned components of the carrier path mounted to the movable body and the image forming unit and the components of the carrier path, such as the carrier rollers and the fixing device, mounted to the static body. The movable body swings especially violently on the side far from the swing center, in other words, the exit of the carrier path, tracing a large arc, and requires high accuracy in relative positioning with respect to the static body. If accurate positioning of the components of the carrier path fails, problems are likely to develop with moving sheet in the carrier path.
Besides, when the movable body is swung around the supporting axis, the movable body experiences a relatively large impact. Possible impact could be taken care of, by providing strength compensation to the supporting axis and associated parts and impact alleviation by means of a hydraulic dumper or another mechanism. However, this will add to the total weight of the image forming apparatus and result in increased load in swinging the movable body, which undesirably degrades operability of the movable body.
To make the entrance of the carrier path (a part near the feeding unit) wide open, the supporting axis and the static body need be separated by a relatively great distance. This however adds to the size of the image forming apparatus and requires increased room for installation including free space to swing the movable body. It therefore becomes difficult to install the apparatus in limited space. If the movable body is provided with a switchback carrier path and a cover body which can swing so as to open the switchback carrier path, the movable body is swung first, and the cover body needs be also swung with respect to the already swung movable body, which adds to difficulty to the removing of sheet.
An object of the invention is to provide an image forming apparatus having a carrier path which can be wide open along the entire length thereof without adding to the size owing to such a configuration that enables a movable body in a main body to slide and optionally a sub-carrier path, being connected to the carrier path at the midpoint thereof, which can be wide open together with the carrier path.
Another object of the invention is to provide an image forming apparatus that can maintain good positional relationship among components forming a carrier path between a static body and a movable body in a main body and also that can position, relative to the image forming unit, an auxiliary device, such as a transfer device, mounted to the movable body with increased accuracy when the movable body is slid closed, owing to a configuration in which the static body or the movable body has a guide member for guiding the slide movement of the movable body.
A further object of the invention is to provide an image forming apparatus which satisfactorily prevents a sheet stuck in the carrier path from falling when the carrier path is opened, owing to a configuration in which either the static body or the movable body has a pair of carrier rollers carrying the sheet.
Yet another object of the invention is to provide an image forming apparatus that can position the auxiliary device, such as the transfer device, relatively to the image forming unit with increased accuracy when the movable body is slid closed, owing to a configuration in which the auxiliary device is provided swingingly to the movable body.
An image forming apparatus in accordance with a first aspect includes: an image forming unit for forming an image on a sheet; a feeding unit for feeding the sheet toward the image forming unit; a discharge unit for discharging the sheet carried from the image forming unit to the outside thereof, and a main body separable into a static body and a movable body along a carrier path extending from the feeding unit to the discharge unit, the static body being provided with the image forming unit, and is adapted so that the movable body is slidable with respect to the static body.
According to the first aspect, the carrier path extending from the feeding unit to the discharge unit can be wide open along the entire length thereof by sliding open the movable body; therefore, sheet stuck in the carrier path, especially, in winding and other parts where sheet is likely to get stuck, can be readily spotted and easily removed. The image forming apparatus thus delivers good operability in sheet removal. The movable body slides and experiences a relatively small impact when slid open; therefore, the movable body no longer needs a complicated supporting mechanism. The image forming apparatus weighs less and requires less installation space.
An image forming apparatus in accordance with a second aspect is such that the feeding unit is provided in plurality and that the main body is separable into the static body and the movable body along the carrier path extending from the plurality of feeding units to the discharge unit.
An image forming apparatus in accordance with a third aspect is such that the carrier path of one of the plurality of feeding units which is located relatively near the image forming unit is connected to the carrier path formed by one of the plurality of feeding units which is located relatively far from the image forming unit.
According to the second and third aspects, the carrier path extending from the plurality of feeding units to the discharge unit can be wide open along the entire length thereof by sliding open the movable body; therefore, sheet stuck near any feeding unit can be easily removed. The image forming apparatus thus delivers good operability in sheet removal.
An image forming apparatus in accordance with a fourth aspect is such that the movable body has guide units for guiding the sheet on which an image is formed by the image forming unit along the carrier path.
According to the fourth aspect, when the movable body is slid closed, the carrier path extending from the image forming unit to the discharge unit can be positioned to a predetermined state by means of a simple configuration; therefore, problems are less likely to occur at junctions of the static body and the movable body in the carrier path.
An image forming apparatus in accordance with a fifth aspect includes: an image forming unit for forming an image on a sheet; a feeding unit, provided below the image forming unit, for feeding the sheet toward the image forming unit; a discharge unit, provided above the image forming unit, for discharging the sheet carried from the image forming unit to the outside; a carrier path extending from the feeding unit to the discharge unit; a sub-carrier path, being connected to the carrier path near an exit thereof, for carrying the sheet carried from the image forming unit in a direction moving away from the discharge unit; and a main body separable into a static body and a movable body along the carrier path, the static body being provided with the image forming unit, and is adapted so that the sub-carrier path extends flatly sideways and that the movable body is sidable with respect to the static body along the sub-carrier path.
With the fifth aspect, all the advantages of the first aspect are available. Further, the sub-carrier path can be wide open, and sheet stuck in the sub-carrier path can be easily removed.
An image forming apparatus in accordance with a sixth aspect is such that the sub-carrier path is shorter than the carrier path.
According to the sixth aspect, the carrier path and the sub-carrier path can be wide open along the entire lengths thereof by sliding the movable body a distance, L+xcex1, which is equal to a sum of the length L of the sub-carrier path and a suitable distance xcex1. Therefore, the movable body needs to be slid a shorter distance, requiring less space to install the image forming apparatus.
An image forming apparatus in accordance with a seventh aspect is such that the sub-carrier path, near an entrance thereof, overlaps the carrier path and from the entrance to an exit thereof, extends flatly in a direction moving away from the discharge unit and that the movable body is sidable along the sub-carrier path.
According to the seventh aspect, the sub-carrier path extending flatly in a direction moving away from the discharge unit, near an entrance thereof, overlaps the carrier path; therefore, the movable body needs to be slid an even shorter distance, requiring even less space to install the image forming apparatus.
An image forming apparatus in accordance with an eighth aspect is such that the sub-carrier path is an entrance of a switchback carrier path for carrying the sheet carried from the image forming unit to an entrance of the carrier path.
According to the eighth aspect, the switchback carrier path can be wide open near the entrance thereof, that is, the exit of the carrier path, which is the most difficult part to carry sheet in the carrier path; therefore, sheet stuck in the carrier path can be readily spotted and easily removed.
An image forming apparatus in accordance with a ninth aspect includes a pair of carrier rollers, mounted to either the static body or the movable body, for carrying the sheet along the carrier path while holding the sheet in between at a position facing the carrier path.
According to the ninth aspect, when the movable body is slid open to open the carrier path, the pair of carrier rollers mounted to the movable body continue holding the sheet in between. Those areas surrounding the carrier path and the user""s hands can be thereby prevented from being smeared with an unfixed toner image on sheet which droops or falls from the carrier path. The sheet stuck in the carrier path can be readily spotted. The image forming apparatus thus again delivers good operability in sheet removal.
An image forming apparatus in accordance with a tenth aspect is such that the static body includes: a control roller for controlling a timing to carry the sheet to the image forming unit; and a guide body for guiding the sheet to the control roller, the control roller and the guide body both being provided between the feeding unit and the image forming unit at a position facing the carrier path.
According to the tenth aspect, even if the carrier path is opened, the control roller for controlling a timing to carry the sheet to the image forming unit is positioned unchanged with respect to the guide body for guiding the sheet to the control roller, for better resist precision. The image is therefore formed on the sheet at an ideal position.
An image forming apparatus in accordance with an eleventh aspect includes: an image forming unit for forming an image on a sheet; a feeding unit for feeding the sheet toward the image forming unit; a discharge unit for discharging the sheet carried from the image forming unit to the outside; a sub-carrier path, being connected to an exit side of a carrier path between the feeding unit and the discharge unit, for carrying the sheet having passed through the image forming unit in a direction different from the discharge unit; and a main body separable into a static body and a movable body along the carrier path, the static body being provided with the image forming unit, and is adapted so that the movable body is slidable with respect to the static body and has a guide unit for guiding the sheet along the sub-carrier path.
With the eleventh aspect, all the advantages of the first aspect are available. Further, the sheet in the carrier path can be carried to the sub-carrier path along the guide unit of the movable body; therefore, by sliding open the movable body, the sub-carrier path can be wide open, facilitating the removal of sheet stuck in the sub-carrier path.
An image forming apparatus in accordance with a twelfth aspect includes: an image forming unit for forming an image on a sheet; a feeding unit for feeding the sheet toward the image forming unit; a discharge unit for discharging the sheet carried from the image forming unit to the outside; a switchback carrier path, being connected to an entrance side and an exit side of a carrier path between the feeding unit and the discharge unit, for carrying the sheet carried from the image forming unit toward the feeding unit; and a main body separable into a static body and a movable body along the carrier path, the static body being provided with the image forming unit, and is adapted so that the feeding unit is provided in plurality and that the movable body has a guide unit, provided below a connection portion where the switchback carrier path is connected to the exit side of the carrier path, for guiding along the carrier path the sheet carried from one of the plurality of feeding units which is located relatively far from the image forming unit to the carrier path formed by one of the plurality of feeding units which is located relatively near the image forming unit.
With the twelfth aspect, all the advantages of the first aspect are available. Further, when the movable body is slid closed, the carrier path connected to the plurality of feeding units can be positioned to a predetermined state by means of a simple configuration; therefore, problems are less likely to occur at junctions of the static body and the movable body in the carrier path.
An image forming apparatus in accordance with a thirteenth aspect is such that the movable body has a guide unit for guiding along the carrier path the sheet carried from the switchback carrier path to the carrier path.
According to the thirteenth aspect, when the movable body is slid closed, a part of the carrier path which is connected to the switching carrier path near the exit thereof can be positioned to a predetermined state by means of a simple configuration; therefore, problems are less likely to occur at junctions of the static body and the movable body in the carrier path.
An image forming apparatus in accordance with a fourteenth aspect includes: a carrier switching body for carrying the sheet carried from the image forming unit by switching between the discharge unit and the sub-carrier path; and a holding body, mounted swingingly to the movable body, for holding the carrier switching body.
According to the fourteenth aspect, the holding body for holding the carrier switching body is mounted swingingly to the movable body; therefore, when the movable body is slid closed, the carrier switching body can be accurately positioned with respect to the carrier path and the sub-carrier path, thereby improving the quality of the image output produced on the sheet. The sheet can be carried in a satisfactory manner in the sub-carrier path in which eet passes after the fixing and tends to be carried only in an unstable manner.
An image forming apparatus in accordance with a fifteenth aspect is such that either the static body or the movable body has multiple guide members for guiding the slide movement of the movable body, and the movable body has an auxiliary device, located among the guide members, for assisting image formation on the sheet in the image forming unit.
According to the fifteenth aspect, the auxiliary device, for example, a transfer device, is mounted to the movable body, among the guide members. Therefore, when the movable body is slid closed, the auxiliary device can be moved toward the image forming unit, while keeping a substantially correct positional relationship. The auxiliary device can thereby be accurately positioned with respect to the image forming unit, which improves the quality of the image formed on the sheet.
An image forming apparatus in accordance with a sixteenth aspect is such that the guide members are disposed on both sides of the carrier path in terms of width thereof and on an entrance side and an exit side of the carrier path.
According to the sixteenth aspect, the auxiliary device is mounted to the movable body in an area formed by the guide members disposed in the back and those disposed in the front as viewed with the image forming apparatus installed in a suitable place; therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit in a stable condition. The auxiliary device can be thereby accurately positioned with respect to the image forming unit, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with a seventeenth aspect is such that the auxiliary device is disposed at the central position among the guide members.
According to the seventeenth aspect, the auxiliary device is mounted to the movable body substantially at the center of an area formed by the multiple guide members; therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit in a stable condition. The auxiliary device can be thereby accurately positioned with respect to the image forming unit, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with an eighteenth aspect is such that either the static body or the movable body has: a guide member for guiding the slide movement of the movable body; and prevention means for preventing the slide movement of the movable body, and there is provided an auxiliary device, located between the guide member and the prevention means, for assisting image formation on the sheet in the image forming unit.
According to the eighteenth aspect, the auxiliary device is mounted to the movable body between the guide member and the prevention means; therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit in a stable condition, and the movable body can be surely kept closed. The auxiliary device can be thereby accurately positioned with respect to the image forming unit, and the relative position is surely maintained, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with a nineteenth aspect is such that either the static body or the movable body has guide members, located near an entrance and exit of the carrier path, for guiding the slide movement of the movable body, and there are provided among the guide members: an auxiliary device for assisting image formation on the sheet in the image forming unit; and prevention means for preventing the slide movement of the movable body.
According to the nineteenth aspect, the guide members are disposed near the top and an bottom of the main body, and sheet stuck in the carrier path can be readily removed, with none of the guide members obstructing the removing action. Besides, the auxiliary device and the prevention means are disposed among the guide members for sliding the movable body; therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit, while keeping a substantially correct positional relationship. The auxiliary device can thereby be accurately positioned with respect to the image forming unit. In addition, the movable body can be slid smoothly and experiences less deformation in the slide movement; as a result, the movable body can be slid straightly.
An image forming apparatus in accordance with a twentieth aspect includes: guide members, disposed on both sides of the carrier path in terms of width thereof, for guiding the slide movement of the movable body; and an auxiliary device, located near the guide members, for assisting image formation on the sheet in the image forming unit.
According to the twentieth aspect, the auxiliary device is located among the guide members disposed on both sides of the carrier path in terms of width thereof therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit, while keeping a substantially correct positional relationship. The auxiliary device can thereby be accurately positioned with respect to the image forming unit, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with a twenty-first aspect is such that there are more guide members on one side of the carrier path in terms of width thereof than on the other side.
According to the twenty-first aspect, there can be less guide members in the front than in the back as viewed with the image forming apparatus installed in a suitable place; therefore, sheet stuck in the carrier path can be readily spotted. Moreover, the guide members present less obstruction to sheet removing action. The image forming apparatus thus delivers good operability in sheet removal.
An image forming apparatus in accordance with a twenty-second aspect is such that one side of the auxiliary device is supported between the guide members on one side and the other side thereof is supported near the guide members on the other side.
According to the twenty-second aspect, the auxiliary device is mounted to the movable body with one of sides of the auxiliary device located near the guide members on the other side and with the other side located between the guide members on the one side; therefore, when the movable body is slid closed, the auxiliary device can be moved straightly toward the image forming unit, while keeping a substantially correct positional relationship. The auxiliary device can thereby be accurately positioned with respect to the image forming unit, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with a twenty-third aspect is such that the auxiliary device is a transfer device of a contact type which contacts the image forming unit, and the transfer device is disposed near the prevention means.
According to the twenty-third aspect, a good positional relationship is always ensured between the sheet and the transfer device, and the prevention means reduces variations in the relationship between the sheet and the rotated transfer device to a minimum. The transfer device can thereby be accurately positioned with respect to the image forming unit, improving the quality of the image formed on the sheet.
An image forming apparatus in accordance with a twenty-fourth aspect is such that the guide members on the other side of the carrier path in terms width thereof are located far from a contact portion where a side of the sheet contacts in the carrier path.
An image forming apparatus in accordance with a twenty-fifth aspect is such that the contact portion is a winding part, a connection portion where the sub-carrier path is connected, or a connection portion where a switchback carrier path is connected.
According to the twenty-forth or twenty-fifth aspect, those guide members in the front as viewed with the image forming apparatus installed in a suitable place can be disposed a distance away from parts of a carrier path where problems are likely to develop with moving sheet. The guide members therefore present less obstruction in removing sheet stuck in the carrier path. The image forming apparatus thus delivers improved operability in sheet removal.
An image forming apparatus in accordance with a twenty-sixth aspect is such that the auxiliary device is disposed swingingly.
According to the twenty-sixth aspect, the auxiliary device is mounted swingingly to the movably body; therefore, when the movable body is slid closed, the auxiliary device can thereby be accurately positioned with respect to the surface of the image forming unit, improving the quality of the image formed on the sheet. Further, since the auxiliary device can thereby be accurately positioned with respect to the surface of the image forming unit, no highly precise sliding means is required to slide the movable body. Costs are saved and the movable body can be slid smoothly.
An image forming apparatus in accordance with a twenty-seventh aspect is such that the auxiliary device is a transfer device for transferring the image formed by the image forming unit onto the sheet.
According to the twenty-seventh aspect, when the movable body, which is sidable by the benefit of the guide members, is slid closed, the transfer device can be positioned with respect to the image forming unit mounted to the static body in a suitable condition. Thus, the quality of the image formed on the sheet is ensured.
An image forming apparatus in accordance with a twenty-eighth aspect is such that the auxiliary device is a transfer device of a contact type which contacts the image forming unit.
According to the twenty-eighth aspect, the transfer device of a contact type is mounted to the movable body which is slidable; therefore, when the movable body is slid closed, the transfer device of a contact type can be positioned with respect to the image forming unit in a predetermined positional relationship, and the quality of the image formed on the sheet is improved.
An image forming apparatus in accordance with a twenty-ninth aspect is such that the transfer device has a connection terminal connected to and disconnected from a power source terminal provided to the static body.
According to the twenty-ninth aspect, the connection terminal is provided to the transfer device which can be accurately positioned with respect to the image forming unit; therefore, when the movable body is slid closed, the connection terminal provided to the transfer device can be surely connected to the power source terminal provided to the static body, which ensures image formation on the sheet. Further, the connection terminal can be surely connected to the power source terminal; therefore, faulty operations due to damage or improper connection of the power source terminal and the connection terminal can be avoided.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.
FIG. 1 is a cross-sectional view of an image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 2 is a cross-sectional view of major components of an image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 3 is a cross-sectional view of an image forming apparatus having a single feeding unit in accordance with the invention, showing a closed carrier path;
FIG. 4 is an enlarged cross-sectional view of the entrance and vicinity of a carrier path in an image forming apparatus in accordance with the invention;
FIGS. 5A-5C are enlarged cross-sectional views of the exit and vicinity of a carrier path in an image forming apparatus in accordance with the invention;
FIG. 6 is a cross-sectional view of a second embodiment of the image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 7 is a perspective view of a fourth embodiment of the image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 8 is a perspective view of a fifth embodiment of the image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 9 is a perspective view of a sixth embodiment of the image forming apparatus in accordance with the invention, showing an open carrier path;
FIG. 10 is a perspective view of the sixth embodiment of the image forming apparatus in accordance with the invention, showing an open carrier path; and
FIG. 11 is a cross-sectional view of major components of an image forming apparatus in accordance with the invention, showing an open carrier path.